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N Sreeram

Publications and source records attributed to N Sreeram.

At least 19 recordsLinked to original sources
PubMed2006

Transhepatic approach for catheter interventions in infants and children with congenital heart disease.

UNLABELLED: We report on our experience with transhepatic access for catheter interventions in six children (age range 2.5 months-9 years). Three had systemic venous anomalies, and one infant a femoral venous occlusion. In two further patients with bradyarrhythmia after a Fontan operation with an intraatrial Gore-Tex tunnel, transhepatic access was chosen to achieve a perpendicular orientation of the transseptal needle to the atrial baffle, allowing puncture of the Gore-Tex membrane. Two of the patients underwent ablation of an accessory pathway; in one an atrial septal defect was closed. A 2.5 month old baby after Norwood I operation, underwent balloon dilation of the pulmonary arteries. Two patients after prior Fontan surgery underwent DDDR pacemaker implantation. The size of the introducer sheath ranged from 4 F up to two 9 F introducers in the same vein for pacemaker insertion. At the end of the procedure, hemostasis was achieved by external compression. RESULTS: Transhepatic access could be established in all six patients (using a mirror image approach in children with left atrial isomerism) and the interventional procedures could be performed as planned. In one patient with implantation of a permanent pacemaker, a subcutaneous hematoma occurred, requiring blood transfusion. CONCLUSION: In selected pediatric patients, transhepatic access for catheter intervention can easily be achieved.

Angioplasty, Balloon↗
PubMed2005

Experience with an ambulatory 12-lead Holter recording system for evaluation of pediatric dysrhythmias.

BACKGROUND: The 12-lead electrocardiogram demonstrates noninvasively many details concerning cardiac arrhythmias and their mechanism, but only for a limited period. A Holter system can record heart rhythm for a longer period, but shows 2 or 3 leads only. An ambulatory 12-lead Holter recording system combines the advantages of both. We report on our experience with the 12-lead Holter system in children. STUDY POPULATION: Twenty-four patients (age range, 3-22 years) underwent one or more 12-lead Holter recordings. Twelve patients had suspected or documented tachyarrhythmia, and 12 patients had suspected or proven long QT syndrome (LQTS). RESULTS: In the tachyarrhythmia group, 4 patients had supraventricular tachycardia and 7 ventricular tachycardia (VT). In the supraventricular tachycardia, group 1 patient had intra-atrial reentrant tachycardia with a single reentrant circuit, whereas another had multiple P-wave morphologies, suggesting multiple circuits. Two others had evidence for concealed atrioventricular accessory pathways. One patient had isolated supraventricular ectopy. In the VT group, 4 patients had uniform VT, and 3 patients had polymorphic VT. One patient with LQTS had macroscopic T-wave alternans. Two others showed intermittent extreme QT prolongation and T-wave notching during 12-lead Holter recording. THERAPEUTIC IMPLICATIONS: Patients with uniform VT underwent catheter ablation, guided in 2 instances by intracardiac pace mapping and comparison with the 12-lead Holter QRS morphology. All reentrant supraventricular arrhythmias with single P-wave morphology were ablated. One patient with intra-atrial reentrant tachycardia and multiple circuits received an antitachycardia pacemaker. In the LQTS group, the neonate with T-wave alternans received mexiletine in addition to beta-blocker therapy. CONCLUSION: In individual patients, the 12-lead Holter system provides important additional information about the arrhythmia and helps to plan appropriate therapy. Intermittent T-wave morphology changes can be diagnosed using 12-lead Holter recordings in patients with LQTS, allowing dynamic T-wave changes to be monitored. In specific cases, this may help identify patients with LQTS and also influence pharmacological therapy.

Adolescent↗
PubMed2005

Catheter ablation of junctional ectopic tachycardia in children, with preservation of atrioventricular conduction.

BACKGROUND: Idiopathic junctional ectopic tachycardia is a rare arrhythmia in children. Several studies have demonstrated that drug therapy is often ineffective and sometimes the only achieved effect is rate control. Early presentation and frequent recurrence are associated with adverse outcome. PATIENTS AND METHODS: Three consecutive children, aged 9, 7 and 12 years respectively, underwent radiofrequency catheter ablation for junctional ectopic tachycardia, after having failed antiarrhythmic drug therapy. The entire His bundle was plotted out and marked, using the Localisa navigation system. The arrhythmia was readily and repeatedly inducible using intravenous isoprenaline infusion and the site of earliest retrograde conduction during tachycardia could be assessed. Ablations were performed in sinus rhythm, empirically targeting the site of earliest retrograde conduction during tachycardia. RESULTS: This approach was successful in abolishing tachyarrhythmia in the first two patients, in whom the successful ablation site was located superoparaseptally. In the third patient, junctional ectopic tachycardia was inducible, despite abolishing retrograde atrial activation, in a septal location on the tricuspid valve annulus. Further ablations in the superoparaseptal region, closer to the His bundle, were successful in rendering tachyarrhythmia noninducible. Over a median follow-up of 10 months, none of the patients has had recurrence of arrhythmia, despite discontinuing all antiarrhythmic medications. CONCLUSIONS: Radio frequency catheter ablation of junctional ectopic tachycardia is feasible with preservation of atrioventricular conduction.

Atrioventricular Node↗
PubMed2005

Radiofrequency catheter septal ablation for hypertrophic obstructive cardiomyopathy in childhood.

Two patients, a 5 year old boy with progressive hypertrophic obstructive cardiomyopathy and increasing symptoms despite appropriate pharmacologic therapy and an 11 year old girl with symptoms of tiredness and peak instantaneous LVOT gradient of 80 and 90 mmHg respectively were considered for radiofrequency catheter septal ablation, to relieve the left ventricular outflow tract obstruction. Via a femoral arterial approach, the His bundle was initially plotted and marked using the LocaLisa navigation system. Subsequently, using a cooled tip catheter a series of lesions was placed in the hypertrophied septum, commencing distally in the ventricle and proceeding towards the aortic valve, taking care to stay away from the His bundle. The procedure was deemed to be completed when the entire extent of the hypertrophied septum had been treated. In the boy the procedure was complicated by two episodes of ventricular fibrillation, requiring DC cardioversion, but without any neurologic sequelae. The peak to peak gradient between left ventricle and aorta was 50 mmHg and 60 mmHg respectively pre-ablation, and remained unchanged immediately after. Both patients were discharged from the hospital 48 hours later. Serial measurement of serum Troponin T and CK-MB isoenzyme confirmed significant myocardial necrosis. Follow-up echocardiography at 7 days and at 6 weeks post-ablation respectively confirmed a beneficial hemodynamic result, with reduction of left ventricular outflow obstruction and relief of symptoms. In young children, in whom alcohol induced septal ablation is not an option, radiofrequency catheter ablation offers an alternative to surgery, with the benefits of repeatability and a lower risk of procedure-related permanent AV block.

Cardiomyopathy, Hypertrophic↗
PubMed2005

Slow pathway ablation in children with documented reentrant supraventricular tachycardia not inducible during invasive electrophysiologic study.

UNLABELLED: Radiofrequency catheter ablation (RFA) has become the procedure of choice for permanent therapy of atrioventricular nodal reentrant tachycardia (AVNRT). This report presents our experience with atrio-ventricular node (AVN) modification in patients with documented narrow complex reentrant SVT, but no evidence for an accessory pathway, and no inducible tachyarrhythmia during invasive electrophysiology (EP) study. METHODS: The study population consists of nine children, age range 6-13 years (median 9) with previously documented SVT who had no tachyarrhythmia inducible during EP study (at baseline and following isoprenaline infusion). Eight of the 9 EP studies were performed under general anesthesia, and one under conscious sedation. An accessory pathway was excluded in all patients by appropriate atrial and ventricular extrastimulus pacing techniques. Eight of the nine patients had dual AV nodal physiology, and one had single AV nodal echo beats. The slow AV nodal pathway was empirically ablated, by applying RF lesions in the right inferoseptal AV groove, achieving catheter tip temperature of 50 degrees C. The appearance of an accelerated junctional rhythm during RF application was deemed to denote a successful application site. AV conduction during RF application was confirmed by incremental atrial pacing. The catheter position, and its relation to the compact AV node was constantly monitored using the LocaLisa navigation system. The end-point was absence of dual AVN physiology, and/or AV nodal echo beats. RESULTS: Successful slow pathway ablation was achieved in all patients. One patient appeared to have two separate slow pathways with different locations and two AH-jumps, which were both successfully ablated. None of the patients had evidence of temporary or permanent AV block at follow-up (median duration 9 months, range 4 to 36 months); none has had recurrence of symptoms or documented tachyarrhythmia. CONCLUSIONS: In children with structurally normal hearts, a previously documented SVT, absence of an accessory pathway and noninducibility of SVT during EP study, empirical slow pathway ablation appears to be justified.

Adolescent↗
PubMed2005

[Electrical heart diseases--therapy during childhood and adolescence].

With increasing experience, radiofrequency catheter ablation of tachyarrhythmia substrates has become first choice therapy for children >4 years of age with recurrent tachyarrhythmia. In younger patients, the risks associated with the procedure (typically procedure-related AV block or possible coronary artery damage) have to be weighed against the natural history of the tachyarrhythmia substrate, and the degree of control achieved with pharmacologic agents. Ablation for postoperative arrhythmias is more complicated, and associated with lower success rates and a higher rate of recurrence (of the same or a new tachyarrhythmia) despite acute procedural success. In this setting, catheter ablation has to be considered in conjunction with further surgery or the use of a defibrillator as a backup device to prevent arrhythmia-related sudden death. Also in inherited arrhythmias as in long QT syndrome and Brugada syndrome, implantable defibrillators have to be considered as a possible therapeutic option for patients with a higher risk for sudden cardiac death, irrespective of age.

Adolescent↗
PubMed2004

Fetal magnetocardiography: the clinician's viewpoint.

The fetal magnetocardiogram (FMCG) can be reliably recorded from approximately the 15th week of gestation onwards. The MCG has the ability to accurately record cardiac time intervals, and to provide a real-time recording that reflects cardiac electrical activity. Standardisation of the recording, signal processing, and measurement techniques can result in data that is reproducible, and when combined with the establishment of normal values for different gestational ages can be of clinical application universally, particularly in selected groups of patients at risk of potentially lethal arrhythmias.

Cardiotocography↗
PubMed2004

[Closure of a ventricular septum defect in a 4-year-old boy during percutaneous heart catheterisation].

A 4-year-old boy in whom a muscular ventricular septal defect (VSD) had been diagnosed at birth presented with limited exercise tolerance and mild cardiomegaly. The moderately large defect was closed with an umbrella device via percutaneous heart catheterisation. Thereafter, his symptoms disappeared and the dimensions of the left heart returned to normal. A VSD occurs in 1.5-3.5 per 1,000 live births. In symptomatic patients with a medium or large-sized VSD, surgical closure is indicated to prevent the development of a fixed pulmonary resistance hypertension, ventricular dysfunction and the risk of endocarditis. Depending on the size and localisation of the defect, closure with an umbrella device may be chosen. The initial results have been promising in children. The safety and efficacy in the long term are still unknown.

Cardiac Catheterization↗
PubMed2004

Combined transhepatic and transjugular approach for radiofrequency ablation of an accessory pathway in a child with complex congenital heart disease.

We report on a boy with recurrent drug resistant atrioventricular reentrant tachycardia. The patient had complex structural heart disease consisting of right atrial isomerism, systemic venous anomaly (mirror image orientation of the intrathoracic veins, hemiazygos continuation to the left-sided superior vena cava, with separate drainage of the hepatic veins into the left-sided atrium, congenitally corrected transposition (ccTGA), pulmonary atresia (PA), ventricular and atrial septal defects (VSD and ASD). At the age of 22 months RF ablation was performed. Access to the heart was obtained by percutaneous puncture of a hepatic vein, the left internal jugular vein, and femoral artery. Earliest retrograde atrial conduction during tachycardia was localized to the free wall of the left-sided AV groove, and ablation in this area was successful. There were no procedure-related complications. RF ablation of accessory pathway is feasible in young children with complex structural heart disease and abnormal systemic venous return. In such patients access to the heart must be planned with the knowledge of the anatomy and judicious use of the hepatic venous approach, which should be done only by experienced investigators.

Catheter Ablation↗
PubMed2004

The Brugada syndrome. Its relevance to paediatric practice.

The diagnostic and therapeutic aspects of Brugada syndrome, one of the important genetic arrhythmias which causes sudden cardiac death in young people, and the relevance of this diagnostic entity to the paediatric population are briefly summarised. The role of diagnostic testing (genetic, pharmacologic and invasive electrophysiologic) for establishing the diagnosis and for risk stratification are discussed. Finally, while the implantable defibrillator is the only therapy of proven effectiveness in preventing sudden cardiac death, alternative therapies which are being considered (pharmacologic, hormonal and catheter ablation) are overviewed. The aim of this manuscript is to raise the awareness among doctors caring for young patients to the possibility of Brugada syndrome in patients presenting with potentially life-threatening symptoms of syncope or near-miss sudden death, and in index patients with a similar family history.

Adolescent↗
PubMed2003

Persistent junctional reciprocating tachycardia in the fetus.

BACKGROUND: Persistent junctional reciprocating tachycardia (PJRT) tends to be a persistent arrhythmia and requires aggressive therapeutic management. Diagnosis and management of this infrequently occurring tachycardia in the fetus at an early stage is of importance for the prevention of congestive heart failure (CHF). METHODS: A retrospective study of four fetuses with supraventricular tachycardia (SVT) of the PJRT type was performed. RESULTS: All had sustained SVT (mean of 228 beats/min) at a mean gestational age of 34 + 5 weeks, with CHF present in two. Three fetuses had prenatal characteristics of PJRT on M-mode echocardiography with a ventriculoatrial (VA)/atrioventricular ratio of > 1 on M-mode echocardiography suggesting a slow conducting accessory pathway. All four fetuses had postnatal confirmation of the diagnosis. Transplacental treatment with flecainide was effective in one patient; sotalol as a single drug or in combination with digoxin was partially effective in the remaining three. Two developed sinus rhythm, with short intermittent periods of tachycardia and decreasing signs of CHF; one case showed a minimal decrease in heart rate. Oral propranolol therapy converted two patients postnatally; in the remaining two patients radiofrequency ablation was performed at the age of 5 months and 6 years. CONCLUSIONS: The characteristics of our prenatal PJRT cases included a sustained heart rate not exceeding 240 beats/min with a long VA interval, the presence of CHF and therapy resistance. Transplacental treatment should be initiated, possibly with a combination of sotalol and digoxin in non-hydropic cases, or flecainide, especially in case of fetal hydrops. Pharmacological therapy is to be preferred postnatally, but radiofrequency ablation seems to be indicated in therapy-resistant cases with CHF, even in the first months of life.

Adult↗
PubMed2002

Endocardial and epicardial steroid lead pacing in the neonatal and paediatric age group.

AIM: To compare the performance of steroid eluting epicardial and endocardial leads in infants and children requiring permanent pacing. METHODS: Evaluation of pacing and sensing characteristics, impedances, and longevity of 159 steroid eluting leads implanted in 95 children. Group A consisted of 24 children weighing less than 15 kg with 15 endocardial leads (five atrial, 10 ventricular) and 19 epicardial leads (five atrial, 14 ventricular). Group B consisted of 71 children weighing more than 15 kg with 106 endocardial leads (56 atrial, 58 ventricular) and 19 epicardial leads (nine atrial, 10 ventricular). RESULTS: Group A: Stimulation thresholds were lower for ventricular endocardial leads at implant (mean (SD) 0.84 (0.54) v 1.59 (0.64) V, p < 0.014) and at two year follow up (ventricular 0.64 (0.24) v 1.65 (0.69) V, p < 0.003). Impedance and sensing thresholds did not differ significantly at implant and follow up. Group B: Stimulation thresholds were lower for ventricular endocardial leads at implant (0.72 (0.48) v 1.48 (0.58) V, p < 0.001) and at follow up (0.88 (0.46) v 1.55 (0.96) V, p < 0.009). Impedance did not differ. Sensing thresholds were also better for ventricular endocardial leads at follow up (9.1 (5.2) v 14.2 (6.4) mV, p < 0.02). Complications requiring intervention occurred in both groups (n = 7 for endocardial v n = 18 for epicardial leads). CONCLUSIONS: Endocardial and epicardial steroid eluting leads have comparable performance in the paediatric population.

Cardiac Pacing, Artificial↗
PubMed2001

Aneurysmal pericardial patch producing right ventricular inflow obstruction.

A 2-month-old infant presented with acute onset of heart failure, having previously undergone anatomical repair of transposition of the great arteries and ventricular septal defect (VSD). Echocardiography demonstrated aneurysmal dilation of the native pericardial patch used for VSD closure, resulting in right ventricular inflow obstruction. The pericardial patch was excised, and the VSD closed using a GoreTex patch.

Aneurysm, False↗